At 6:41 this morning the Seattle Times reported that light rail service between Northgate and the Capitol Hill station in downtown was temporarily suspended due to a “ventilation safety fault”. That sounds like a relatively minor problem ST will eventually figure out, but this morning it is a major inconvenience for thousands of North Seattle commuters. It also highlights the inherent vulnerability of rail systems. All it takes is one piece of track or one station to have a problem and it shuts down a large part of the system.